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Views: 0 Author: hu Publish Time: 2021-08-22 Origin: dapeng
Lasers are synonymous with precision, but generally speaking, there is room for improvement. A "perfect" laser emits a light at a specific wavelength. The light is emitted from the laser. After the laser oscillates, one or more longitudinal modes will be generated. The frequency range of each longitudinal mode is the "line width" of the laser. Narrowing the linewidth as much as possible is one of the goals of laser research. German researchers have now developed the world's smallest linewidth laser with a linewidth of only 10 mHz (0.01 Hz).
Generally, the best lasers can have a linewidth as narrow as a few kHz, but for particularly precise instruments, such as optical atomic clocks, it needs to be narrowed further. Another way to measure the quality of a laser beam is the stability of the light frequency: after a period of time, the oscillations of the light waves will be out of sync, so a laser beam can maintain a longer "perfect" time, and its quality will become better. Good.
The new laser jointly developed by scientists from the German Federal Institute of Physics and Technology (PTB) and the American Astrophysics Joint Laboratory (JILA) performs well in these two fields. Except for its very small line width of 10 mHz, its light wave can remain stable for 11 seconds. At this time, the beam extends about 3.3 million kilometers, which is about 10 times the distance between the earth and the moon.
In fact, the new laser is very accurate and difficult to compare with existing lasers. In order to prove its value, the team developed two lasers and compared them with each other. The two devices are made of Fabry-Pérot silicon resonators and contain two fixed mirrors facing each other. Since the length of the resonator determines the frequency of the light wave, the researchers used a 21cm long resonator to obtain the ideal laser beam. The researchers used such precise measurements to protect the instrument from other factors, such as pressure, vibration, and temperature.
Researchers are using this new type of laser with extremely small line width to make more accurate atomic clocks and make more precise measurements of ultra-cold atoms. Researchers believe that by adjusting the composition of the mirror and finding a way to reduce the internal temperature of the resonator, the line width can be further narrowed, even reaching below 1 mHz.
The results of this research were published in the journal Physical Review Letters.